.\"	$OpenBSD: fpgetmask.3,v 1.9 2013/06/05 03:39:22 tedu Exp $
.\"	$NetBSD: fpgetmask.3,v 1.3 2001/09/16 02:57:03 wiz Exp $
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Ross Harvey.
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.Dd $Mdocdate: June 5 2013 $
.Dt FPGETMASK 3
.Os
.Sh NAME
.Nm fpgetmask ,
.Nm fpgetround ,
.Nm fpgetsticky ,
.Nm fpsetmask ,
.Nm fpsetround ,
.Nm fpsetsticky
.Nd IEEE FP mode control
.Sh SYNOPSIS
.In ieeefp.h
.Ft fp_except
.Fn fpgetmask void
.Ft fp_rnd
.Fn fpgetround void
.Ft fp_except
.Fn fpgetsticky void
.Ft fp_except
.Fn fpsetmask fp_except\ mask
.Ft fp_rnd
.Fn fpsetround fp_rnd\ rnd_dir
.Ft fp_except
.Fn fpsetsticky fp_except\ sticky
.Sh DESCRIPTION
A rounding mode is one of
.Dv FP_RZ , FP_RM , FP_RN ,
or
.Dv FP_RP ,
for rounding towards zero, rounding
.Pq Em Minus infinity
down, rounding to
.Em nearest ,
and rounding
.Pq Em Plus infinity
up.
The default mode is
.Dv FP_RN .
.Pp
An
.Ft fp_except
value is a bitmask specifying an exception type and containing any of
the values listed below.
.Bl -column FP_X_UFLxx -offset indent
.It Dv FP_X_INV Ta Invalid\ Operation
.It Dv FP_X_DZ Ta Division\ by\ zero
.It Dv FP_X_OFL Ta Overflow
.It Dv FP_X_UFL Ta Underflow
.It Dv FP_X_IMP Ta Imprecision (inexact)
.It Dv FP_X_DNML Ta Denormalization Pq amd64 and i386 only
.El
.Pp
The
.Fn fpsetmask
function will cause future operations with the specified result status to
raise the
.Dv SIGFPE
exception.
The
.Fn fpsetround
function will cause future operations to use the specified dynamic mode.
.Bl -tag -width Note:x
.It Em Note :
On some architectures, instructions can optionally specify static
rounding modes and exception enables that will supersede the specified
dynamic mode.
On other architectures, these features may not be fully supported.
.El
.Pp
The
.Fn fpsetsticky
function will set or clear the specified exception history bits.
.Sh RETURN VALUES
The
.Fn fpgetround
and
.Fn fpsetround
functions return the
.Pq previous
rounding mode.
The
.Fn fpgetmask ,
.Fn fpsetmask ,
.Fn fpgetsticky ,
and
.Fn fpsetsticky
functions return the
.Pq previous
exception mask and exception history bits.
.Sh SEE ALSO
.Xr sigaction 2
